Candolfi C, Aydemir U, Koza M M, Baitinger M, Grin Yu, Steglich F
Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany. Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine, Parc de Saurupt, CS 50840 F-54011 Nancy Cedex, France.
J Phys Condens Matter. 2015 Dec 9;27(48):485401. doi: 10.1088/0953-8984/27/48/485401. Epub 2015 Nov 16.
We report inelastic neutron scattering (INS) measurements on the polycrystalline oP60-type clathrate BaGe5, whose crystal structure is related to the type-I clathrate Ba8Ge43□3 and to the cP124-clathrate Ba6Ge25. Our results show that BaGe5 exhibits a similar phonon density of states (PDOS) in the energy range 0-40 meV with respect to Ba8Ge43□3. The low-energy region of the PDOS spectrum (0-10 meV) consists of two peaks at 4.1 and 6.2 meV likely related to Ba-weighted modes. Compared to Ba8Ge43□3, the low-energy region of the phonon spectrum of BaGe5 shows a more complex structure, likely reflecting the presence of three distinct crystallographic sites for Ba. The specific heat data of BaGe5, reexamined in light of the INS results, indicate that the Ba-weighted modes dominate the low-temperature behavior of Cp.
我们报道了对多晶oP60型笼合物BaGe5的非弹性中子散射（INS）测量结果，其晶体结构与I型笼合物Ba8Ge43□3以及cP124笼合物Ba6Ge25相关。我们的结果表明，相对于Ba8Ge43□3，BaGe5在0 - 40毫电子伏特的能量范围内表现出相似的声子态密度（PDOS）。PDOS谱的低能量区域（0 - 10毫电子伏特）在4.1和6.2毫电子伏特处有两个峰，可能与Ba加权模式有关。与Ba8Ge43□3相比，BaGe5的声子谱低能量区域显示出更复杂的结构，这可能反映了Ba存在三个不同的晶体学位置。根据INS结果重新审视的BaGe5的比热数据表明，Ba加权模式主导了Cp的低温行为。
